Multiple mating and cooperative breeding in polygynandrous alpine accentors. II. Male mating tactics
I studied the timing and frequency of male copulatory behaviour in alpine accentors, Prunella collaris, in Japan, with respect to dominance status, age and development of the cloacal protuberance. Males used one of three mating tactics depending on their dominance status. Alpha males guarded several females in succession, but only during the females' fertile period, while gamma males copulated rarely and only with unguarded females. The tactics of beta males were flexible: with unguarded females they usually adopted a frequent-copulation tactic, but when two females had synchronous egg-laying periods, beta males associated closely with whichever female the alpha male left unguarded. When alpha males closely guarded a female, beta males guarded this same female for short periods before and after the guarding period of the alpha male. Subordinate rank restricted a male's opportunities for mating but males of all dominance ranks were sexually active and had fully developed cloacal protuberances. Frequent copulation plus part-time mate guarding (as found in beta males) and opportunistic copulation (as found in gamma males) appears to be a conditional strategy whereby young, subordinate males are 'making the best of a bad job'. A long-term study over 10 years showed that males moved up in social rank with increasing age but 78.9% of males remained subordinate because alpha males occupied the top rank for much of their lifetime. Copyright 1998 The Association for the Study of Animal Behaviour.
Nakamura
M
Department of Biology, Faculty of Science, Osaka City University, Japan